The embodiments of the invention relate to technology for polishing substrates that are work pieces that require highly planar processing such as silicon wafer semiconductor substrates and glass substrates, and particularly it relates to technology making possible the achievement of regeneration of polishing pads used when polishing the surface of such substrates.
As is well known, when manufacturing semiconductors, polishing is carried out to planarize the substrate surface of silicon wafers, semiconductor substrates, glass substrates and the like comprising the constituent materials of semiconductors. Such polishing processes, generally, are carried out by polishing by directly fixing a disc shaped polishing pad made of synthetic resin material or the like atop the rotation table of the polisher with double sided tape, and while supplying polishing solutions containing polishing particles (grit) utilizing the mutually rotary motion of polishing pad and substrate
Moreover, resin pads made of foamed or unfoamed polyurethane and the like may be used as the polishing pad for this kind of polishing process as described in Japanese Laid Open Patent Application 2002-11630 (hereby incorporated by reference as Patent Reference 1). Additionally, the polishing surface of such polishing pads, in many cases, is subjected to concentric or grid-like or radial grooving or the like, and the bubbles of the foamed resin are opened to the surface.
Furthermore, in polishing processes where a polishing pad is used, when the kind of substrate product that is the object of the polishing is changed, it is sometimes necessary to tear the polishing pad used in polishing from the rotation table and exchange it with another polishing pad. Moreover, for example, even in cases such as where a polishing pad that has been worn down during the polishing process is reprocessed by such means as putting grooves into the surface by separate processing equipment, it is necessary to tear the polishing pad off of the rotation table.
However, because resin pads in the form of a thin disc are securely fixed with adhesive tape to the rotation table of the polishing equipment, when these polishing pads are torn off of the rotation tables, damage to the polishing pad such as bending and breaking, wrinkling, tearing and the like are easily produced. For that reason, there exists the problem of it often being unavoidable to have to throw away such polishing pads before the end of their useful life without being able to reuse them.
Moreover, there is also a problem with the practice of tearing these polishing pads from the rotation table while exercising scrupulous care so as not to damage them, in that the operator must bear the considerable burden of the exercise of the requisite skill and caution. Additionally, because a considerable amount of time is required for the process of tearing the polishing pad off of the rotation table, there is also the problem that high value polishing equipment must be stopped over a long period of time and the operation time of the equipment is thus limited.
Japanese Laid Open Patent Application 2001-54859 (hereby incorporated by reference as Patent Reference 2) offers a structure in which, together with integrally forming a plate shaped support layer directly to the back surface of the polishing pad, by holding fast this support layer to the rotation table of the polishing device using magnetism or low pressure, it is possible to easily remove the polishing pad from the rotation table. However, not only is it difficult to form the support layer integrally directly onto the back surface of the polishing pad, but even if integral formation of the support layer with the polishing pad is obtained, there are yet problems in actual utilization.
Probably, in Patent Reference 2, examples of fixing the polishing pad to the rotation table using magnetism or reduced pressure are given, however, it is extremely difficult to exert sufficient magnetic force to introduce the thick rotation table to the thin support layer, and moreover, even in the case of the use of the force of low pressure, it is difficult to exert sufficient adsorptive force without forming a closed region between the planar support layer and the rotation table that is definitely cut off from the outside atmosphere. Again, additionally, in Patent Reference 2, a structure in which the back of the support layer is fixed to the rotary surface layer with tape is also disclosed, however, it is merely a thin planar support layer and covering the back surface of the polishing pad, and adequate stiffness is not achieved. When the supporting layer is torn off of the rotation table, just as with the simple structured polishing pad, such damage as bending and breaking and wrinkling and the like is produced.
Additionally, there is also the problem that whether with the polishing pad disclosed in Patent Reference 2 or the aforementioned polishing pad with the unitary structure referred to above, from the fact of having the simple circular shape, these are difficult and time consuming to center (centering) accurately on the rotation table.